Two wheat curl mite, Aceria tosichella Keifer, biotypes have different responses on wheat

The wheat curl mite, Aceria tosichella, is one of the most important world arthropod pests of wheat and vectors wheat streak mosaic virus (WSMV), the most significant wheat virus in North America. Varieties with moderate levels of mite resistance or virus resistance exist, but none contain both. Further, mite virulence to wheat resistance exists in North America and Australia, further complicating the development of mite-WSMV management strategies. We have assessed population lineages of A. tosichella in North America and established their relationship with global populations. Based on internal transcribed spacer (ITS1) sequences,  two major A. tosichella biotypes exist in North America - a Nebraska biotype similar to Australia biotype 2; and a biotype occurring in Kansas and Montana, USA and Alberta, Canada populations similar to and aligned with Australia biotype 1. These results are providing a platform for our future studies to understand global A. tosichella movement and spread. Furthermore, we have used molecular markers linked to the Cmc4 gene for A. tosichella resistance and markers linked to the Wsm2 wheat streak mosaic resistance gene to identify wheat plants in F₄ populations with both A. tosichella and WSMV resistance. Finally, A. tosichella virulence patterns in the U.S. hard red winter wheat production area have not been determined in 10 years, and our recent results have determined A. tosichella virulence patterns with both A. tosichella- and WSMV resistant wheat plants.